A couple of store worlds registered to my account

RexyStorms​  Which worlds appeared on your account?  Riverview is free for everyone, and Barnacle Bay is free to download (but doesn't necessarily show as registered on My Page) for many players.  The latter is because of some issue with pre-orders for Island Paradise, but many people received it without having pre-ordered IP.  (I got a copy when I registered IP several years later.)

I very much doubt you'd have anything else you never paid for on your account though.  At least, I haven't heard of it happening, and as far as I've ever seen, there's also no way for EA support to add a world to an account even when the player HAS paid for it.

I've not heard about those two being free or how to acquire them. The ones on my account are Monte Vista and Sunlit Tides. 

Hey RexyStorms​, 

Echoing puzzlezaddict​, it's extremely unlikely for you to have access to worlds you haven't purchased previously. So you've likely purchased both Monte Vista and Sunlit Tides in the past, perhaps using the EA account that was merged into your current account. I'd sign in to both EA accounts and individually check your purchase history on the Sims 3 Store for those worlds. 

Live support would be able to take a look for you as well and give a more definitive answer, as we can't discuss account information here on the forums. Thanks! 

It could very well be just that my memory isn't reliable. Could be I had them on the other account. But I can't really check that myself as the account doesn't exist since the merge. Unless I misunderstood. I'll check the purchase history on my main at least.